Store this manual in an easily
accessible place for quick
reference.
User’s
Manual
WARNING
CAUTION
CAUTION
CAUTION
WARNING
WARNING
CAUTION
<Main unit> <Clamp sensor>
DISP key
(to switch displays)
terminal
Data hold key
Polarity mark
Battery level
Zero ADJ.mark
Main display
WARNING
CAUTION
< correct >
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - TestEquipmentDepot.com
CL420
Clamp-on Process Meter
Thank you for purchasing our Clamp-on Process Meter.
This manual describes the specifications and handling
precautions of the Clamp-on Process Meter.
Before using this product, thoroughly read this manual
to understand how to use it properly.
Contact information of Yokogawa offices worldwide is
provided on the following sheet.
PIM 113-01Z2: Inquiries List of worldwide contacts
November 2017 (YMI)
1. Regarding the Safe Use of This Product
This product is designed to be used by a person with
specialized knowledge.When operating the instrument,
be sure to observe the cautionary notes given below to
ensure correct and safe use of the instrument.
If you use the instrument in any way other than as
instructed in this manual, the instrument's protective
measures may be impaired.
This manual is an essential part of the product;
keep it a safe place for future reference.
YOKOGAWA is by no means liable for any damage
resulting from use of the instrument in contradiction to
these cautionary notes.
The following safety symbols are used on
the instrument and in this manual.
Indicates a hazard that may result in the loss of life or
serious injury of the user unless the described instruction
is abided by.
Indicates a hazard that may result in an injury to the
user and/or physical damage to the product or other
equipment unless the described instruction is abided by.
Danger! Handle with Care.
This mark indicates that operator must refer to
an explanation in the instruction manual in order
to avoid risk of injury or death of personnel or
damage to the instrument.
Do not apply around or remove from
HAZARDOUS LIVE conductors.
This symbol indicates power on/off.
This symbol indicates direct current (DC).
IM CL420-EN
4th Edition
■ Strictly observe the following cautionary notes in
order to avoid the risk of injury or death of
personnel or damage to the instrument due to
hazards such as electrical shock.
• This instrument is a current measuring device (sensor).
Do not use for any other purpose.
• Do not use the instrument if there is a problem with
its physical appearance.
• Do not use this product in a place where an explosive
gas or vapor is present.
• To avoid a short-circuit or an accident to personnel,
use this product within the RATED circuit-to-earth
voltage. If you mistakenly clamp a wire whose voltage
exceeds the RATED circuit-to-earth voltage of
this product, dangerous high voltage may appear at
the analog output terminal.
For example, if you short the item under measurement
with a metal part of the transformer jaw, an arc
discharge may occur, which could damage the item
under measurement.
• Do not use the product when there are raindrops or
droplets of condensed water on its surface, or if your
hands are wet.
• The barrier is there to protect you from touching
the HAZARDOUS LIVE conductor.
Be careful not to reach the barrier when using
the instrument.
• Safety protectors such as rubber-insulated gloves
should be worn to prevent electrical shock when using
the instrument.
• Do not open the battery cover during a measurement.
• Do not measure AC currents.
• Do not use deteriorated or defective output cables.
• Do not use the instrument if the case or cable is
damaged or not attached.
Do not attempt to repair/modify the product yourself,
as doing so is extremely dangerous.
Should an abnormality or failure in the product be
found, contact the vendor from which you purchased
the product.
The instrument is for domestic use (Class B) and meets
the electromagnetic compatibility requirements.
• The clamping jaws are is precision assembled to
ensure high performance. When using the clamp,
do not apply intense mechanical shock, vibration or
force to the clamping jaws.
• If dust or any other foreign matter gets in the clamping
jaws, do not close the clamping cores tight.
First remove the dust and then make sure the clamping
cores on both sides close smoothly.
• Do not expose the instrument to direct sunlight, high
temperature, humidity or dew.
• This instrument is not water/dust proof. Do not use it
in a dusty environment or where it will get wet.
• Always turn off power after using the instrument.
If the instrument is not used for prolonged period,
remove the batteries.
• Use a damp cloth or cotton swab with neutral
detergent or water for cleaning the instrument.
Do not use abrasives or solvents.
■ Measurement category
Do not use the CL420 for measurements in locations
that fall under Measurement Categories
II, III, and IV.
The CL420 is designed for
measurement category O (Other).
Measurement
category
O
None
[
]
Other
CAT II
CAT III
CAT IV
Description Remarks
Other circuits that are not
directly connected to MAINS.
For measurements performed
on circuits directly connected
to the low voltage installation.
For measurements performed
in the building installation.
For measurements performed
at the source of the low-voltage
installation.
Circuits not
connected to a
mains power source.
Appliances,
portable equipment,
etc.
Distribution board,
circuit breaker, etc.
Overhead wire,
cable systems, etc.
2. Feature
● Instrumentation signal (DC4–20mA) measurement
● DC current (0-100mA) measurement without
bisconnecting the electrical circuit.
● LED light for illuminating the measurement spot
● Auto-power-off function
● Display (calculation) of Span (%)
● Analog output function to output the measured results
to a recorder, digital multimeter (DMM) or logger.
● Data hold function
3. Specification
3.1 Accuracy
Condition: 23±5ºC, 75% RH or less
(1) DC current (AUTO RANGE)
Range Display range
20 mA 0.00 to ±21.49 0.00 to ±21.49 0.2 + 5
100 mA ±21.0 to ±126.0 ±21.0 to ±120.0 1.0 + 5
Condition of accuracy:
Response time:
(2) Analog output function
Range
20 mA 0.00 to ±21.49 0.0 to ±214.9
100 mA ±21.0 to ±126.0 ±210 to ±1260
Response time:
• Outputs DC voltage (10 mV/mA) corresponding to
• Outputs 0 mV at range change.
• 1300mV is output when the display shows “OL”.
• Output impedance : approx. 5 kΩ
After power-on, open and close the jaws two
or three times.
After zero-adjustment
*1: The accuracy for the 20 mA range is the result
of averaging five measurements.
Approx. 1.5 seconds
(Approx. 2.5 seconds at range change)
Display range
Add approx. 0.5 s to the current measurement
response time.
the reading.
(-1300mV for “-OL”)
3.2 General Specification
Display: LCD
Measurement cycle:
Operating temperature and humidity:
Storage temperature and humidity:
Power supply: AA-size battery x 4 pcs.
Battery life: Approx. 60 continuous hours
-10 to +50ºC, 85%RH or less (no condensation)
-20 to +60ºC, 85%RH or less (no condensation)
Accuracy : ±(% of reading + digits)
(mA)
(mA)
Guaranteed accuracy
(mA)
Output voltage
(mV)
DCA Accuracy
DCA Accuracy
Approx. 0.6 seconds
(Using alkaline LR6 is recommended.)
(using alkalin battery, backlight and
LED light OFF)
DCA
Accuracy
Accuracy
(mV)
Accuracy of
± 0.5
Accuracy of
± 3
Auto-power-off:
Power off function operates about 10 minutes after
the last switch operation.This function is disabled
when a cord is connected to the OUTPUT terminal.
Temperature coefficients:
Add 0.1 x specified accuracy/ ºC
(at -10 to 18ºC, 28 to 50ºC)
Insulation resistance:
100 MΩ or more/ 1000 VDC
Between electrical circuit (core) and case
Withstand voltage:
2210 VAC for 5 sec.
Between electrical circuit (core) and case
Measurble conductor diameter :
6 mm maximum
The RATED circuit-to-earth voltage : 42 Vpk
Maximum allowed current : 120 mADC
Influence of external magnetic field :
Earth magnetism (0.20 mA) or less
Dimensions:
Main unit
Clamp sensor
Cable length Approx. 700 mm
Weight: Approx. 290 g (including batteries)
Accessories: Soft case (93045)
Optional
accessories
Safety standards: EN 61010-1, EN 61010-2-030,
Environmental conditions:
EMC standards: EN 61326-1 ClassB, EN 61326-2-2,
*1
Environmental standard: EN 50581
:
Operating altiude 2000 m or less,
indoor use, pallution degree 2
EMC Regulatory Arrangement in Australia and New Zealand
Korea Electromagnetic Conformity Standard
( 한국 전자파적합성기준 )
Monitoring and control instruments including
industrial monitoring and control instruments
Approx. 111(H) x 61(W) x 40(D) mm
Approx. 104(H) x 34(W) x 20(D) mm
AA-size Alkaline battery (LR6) 4 pcs.
User’s manual
Output cable (98076)
Output cable for screw terminal
(98077)
EN 61010-2-032
EN 55011 Class B Group 1
4. Components
4.1 Main Unit and Clamp Sensor
Transformer
Jaws (core)
Barrier
Trigger
Light key
Zero ADJ. key
Power key
LED light
LCD
Cable
Analog output
6. Operating Instructions
• Do not use the instrument if it is damaged.
Doing so poses a risk of electrical shock and may
result in inaccurate measurements.
• When using the analog output function, only use
the dedicated output cable (98076 or 98077).
• Be careful not to across the barrier when using
the instrument.
• Do not use the instrument with currents that exceed
the maximum allowed current.
Doing so may damage the instrument.
• A dirty clamp sensor can cause large measurement
errors. Check that the clamp sensor, the item under
measurement, and other relevant items are not dirty
before making measurements.
We recommend that you use an air blower to clean
the clamp sensor jaws (core).
• Take sufficient care to not to apply shock, vibration o
excessive force when opening and closing the clamp
sensor. Otherwise, accurate measured results may
not be obtained. Please open and close the sensor
lightly.
6.1 For Precise Measurements
● Before measurement, with the power turned on,
open and close the clamp sensor two or three times.
● To reduce the influence of temperature, noise,
and other external factors on measurements, perform
“ zero adjustment ”.
● Drastic changes in input current or excessive current
can cause the zero point to drift.
Disconnect the clamp sensor from the conductor to
perform “ zero adjustment ”.
● Position the conductor in the center of the clamp to
make measurements.
● Check that the jaws are fully engaged.
● We recommend that you make several measurements
and compare the results to reduce the influence of
measurement conditions.
[ Zero Adjustment ]
To reduce the effects of external magnetic fields,
move the clamp sensor as close to the conductor
under measurement as possible, align the polarity
arrow with the measurement direction, and press
the ZERO ADJ key.
(Do this without clamping the conductor and with
the transformer jaws closed.)
The
approximately 1 second.
mark is displayed on the LCD for
6.2 Measurement
4.2 LCD
Sub display
indicator
Hold mark
Before making measurements, be sure to open and
close the clamp sensor and perform zero adjustment.
See section 6.1, "For Precise Measurements."
Push the trigger to open the transformer jaws.
Clamp one of the conductors that you will measure.
(see the figure below)
The measured current appears in the main display of
the LCD.
• If the measured current is negative, the current is
flowing in the direction opposite to the clamp arrow.
5. Before Making Measurements
5.1 Turning On the Power
Hold down the Power key for about 2 seconds.
(1) Check the remaining battery.
For further details, see “8. Battery Replacement”.
(2) Check that Data hold function is not enabled.
( mark is not displayed.)
5.2 Turning Off the Power
Hold down the Power key again.
(for about 2 seconds.)
For further details, see “7.2 Auto-power-off function”.
< wrong >
IM CL420-EN <P2>
DMM or the like
1 2 3 4
(Blinking)
WARNING
CAUTION
6.3 Span Display (20 mA Range only)
CAUTION
The sub display shows a percentage in the range
4 mA (0%) to 20 mA (100%).
The shows the relationship between span values (%)
and the measured values (mA).
Measured values
(mA)
-20.00 100.0
0.00 -25.0
2.00 -12.5
4.00 0.0
12.00 50.0
20.00 100.0
100.0 ---
Span display
(%)
The percentage value is calculated based on the
following formula, assuming the measured value as X.
Span display range = ( |X| - 4.00)×6.25 (%)
6.4 Switching between the Main Display and
Sub Display (20 mA range only)
Check that the main display (unit) and sub display (unit)
are displaying values properly.
Press the DISP key to switch between the main and
sub displays.
6.5 Over Range (Load) Indication
When the input exceeds the maximum measuring
range (126.0mA), “OL” or “-OL (for negative values)”
is indicated on the display.
When the range reaches 100mA, bars “---” are
displayed instead of the percentage value.
7. Other Functions
7.1 Data Hold Function
This is a function to freeze the measured value on
the display.
Press the Data hold key once to freeze the reading.
The reading will be held regardless of subsequent
variation in input.
The Data hold mark "
display while the instrument is in the Data Hold mode.
To exit Data Hold mode, press the Data hold key
again.
7.2 Auto-Power-Off Function
The instrument automatically powers off about
10 minutes after the last operation.
This function is disabled when a cord is connected
to the analog output terminal.
[ To cancel the Auto-power-off function ]
Hold down the Data hold key while pressing the
power key.
The instrument is turned on and then “
is indicated for about 1 second.
[ To enable the Auto-power-off function once again ]
Press the power key to turn off the power.
Press the power key (about 2 seconds) to turn on
the power.
(The auto-power-off function is enabled again.)
" is indicated on the
(P.oFF)”
7.3 Backlight and LED Light
Press the Light key to turn on or off the LED light and
LCD backlight. These lights automatically turn off
when 2 minutes elapse after the last key operation.
[ To cancel the auto off function ]
Hold down the Data hold key while pressing the power
key.
The instrument is turned on and then “
(L.oFF) ”
is indicated for about 1 second.
[ To enable the Auto-power-off function once again ]
Press the power key to turn off the power.
Press the power key (about 2 seconds) to turn on
the power.
(The Auto-power-off function is enabled again.)
7.4 Analog Output Function
DC voltage signal corresponding to the measured
(display) result is output from the Analog output
terminal (10 mV/mA).
The output can be recorded and stored on a recorder,
a digital multimeter (DMM) or logger connected to
the instrument by using a dedicated output cable
(98076 or 98077).
When connecting the output cable to the instrument,
the sub display shows “
(OUT)” for 1 second.
When making a long continuous measurement:
• Warm up the instrument for several tens of minutes
after powering it on, and then start a recording.
• Readings will vary when the ambient temperature
changes.
The temperature coefficients provided in chapter 3,
“Specifications”, and fluctuations at zero
(about 20 counts of fluctuation when temperature
changes by 10ºC) should be taken into
consideration.
Output Cable
(98076)
8. Battery Replacement
8.1 Battery State Display
The remaining battery power is displayed using the
following four battery levels.
Replace the batteries as soon as the low battery mark
“
(blinking) ” appears.
Alkaline batteries (four) are recommended.
8.2 Battery Replacement
Ensure that the clamp sensor is disconnected from
the object under test, and that the instrument is
powered off when opening the battery cover for battery
replacement.
(Remove the optional output cable if it is connected.)
• Do not mix batteries of different types or new batteries
with used ones.
• Make sure the polarities of the new batteries are
exactly as shown on the battery holder.
When the low battery mark “
(blinking) ” appears,
measurement accuracy is not guaranteed.
Replace the batteries quickly.
• If the battery is completely flat, the LCD will
not turn on, and the mark will not appear.
[ How to replace batteries ]
(1) Power off the instrument.
(2) Remove the screw on the back of the casing and
remove the battery cover.
(3) Take the batteries out of the housing and replace
the batteries with new ones.
(4) Close the casing and fasten it with the screw.
9. Meintenance
[ Contacting of Services ]
Please contact one of the Yokogawa sales offices
listed of this manual or the sales representative from
which you purchased the instrument.
[ Calibration Cycle ]
It is recommended that the instrument be calibrated
once a year.
10. Sales in Each Country or Region
10.1 Disposing the Product
Waste Electrical and Electronic Equipment
(WEEE), Directive
(This directive is valid only in the EU.)
This product complies with the WEEE directive
marking requirement.
This marking indicates that you must not discard
this electrical/electronic product in domestic
household waste.
10.2 How to Replace and Dispose the Batteries
EU Battery Directive
(This directive is valid only in the EU.)
Batteries are included in this product.
When you remove batteries from this product and
dispose them, discard them in accordance with
domestic law concerning disposal.
Take a right action on waste batteries, because
the collection system in the EU on waste batteries
are regulated.
Battery type: Alkaline dry cell
Product Category
With reference to the equipment types in
the WEEE directive, this product is classified as
a “Monitoring and Control instruments” product.
When disposing products in the EU, contact your
local Yokogawa Europe B.V. office.
Do not dispose in domestic household waste.
Notice:
This marking indicates they shall be sorted out and
collected as ordained in the EU battery directive.
How to remove batteries safely:
For further details, see " 8. Battery Replacement."
10.3 Authorized Representative in the EEA
Yokogawa Europe B.V. is the authorized representative
of Yokogawa Test & Measurement Corporation for
this product in the EEA.
(EEA: European Economic Area)
To contact Yokogawa Europe B.V., see the separate
list of worldwide contacts, PIM 113-01Z2.
10.4 For the Pollution Control of Electronic and Electrical Products of the People's Republic of China
They are applicable only in China.
产品中有害物质的名称及含量
有害物质
部件名称
框架（塑料） ○ ○ ○ ○ ○ ○
线路板 ASSY × ○ × ○ ○ ○
导线 × ○ ○ ○ ○ ○
电池 × ○ ○ ○ ○ ○
<选购>
输出 CABLE
98076
输出 CABLE
98077
○： 表示该有害物质在该部件所有均质材料中的含量均在 GB/T 26572 规定的限量要求以下。
×： 表示该有害物质至少在该部件的某一均质材料中的含量超出 GB/T 26572 规定的限量要求。
环保使用期限 : 该标识适用于 SJ/T 11364 中所述，在中华人民共和国销售的电子电气产品
铅
（Pb）
× ○ ○ ○ ○ ○
× ○ ○ ○ ○ ○
的环保使用期限
只要您遵守该产品相关的安全及使用注意事项，在自制造日起算的年限内
则不会因产品中有害物质泄漏或突发变异，而造成对环境的污染或对人体及
财产产生恶劣影响
注）
该年数为“环保使用期限”，并非产品的质量保证期
零件更换的推荐周期，请参照使用说明书
（Hg）
。
。
汞
镉
（Cd）
（Cr (VI)）
。
六价铬
多溴联苯
（PBB）
，
。
多溴二苯醚
（PBDE）
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